The present invention relates to the field of simulating spatialized 3 dimensional (3D) audio effects around a listener via headphones or the like and, in particular, discloses a compact system for audio simulation.
Various systems have been proposed for the simulation of “out of head” audio effects for headphone listeners. Most traditional headphone arrangements do not include this processing so that when a listener listens on headphones to an audio track designed to be played over stereo loudspeakers or multi-formatted loudspeakers, the sound appears to emanate from inside the listener's head.
A number of systems have been proposed and are well known for providing the effect of spatializing the audio signals, including giving a listener using headphones the illusion that he or she is listening to sound sources located around the listener. Example of such systems can be found in U.S. Pat. No. 6,574,649 issued Jun. 3, 2003 to inventor McGrath, and U.S. patent application Ser. No. 09/647,260 filed Jan. 6, 1999 to inventors McGrath, et al.
Real listening rooms are known to produce reverberation. It is desirable for a headphone spatialization system to include a simulation of the reverberations that occur in a listening environment. It is further desirable to so provide headphone spatialization and realistic simulation of the reverberation at a reasonable cost, e.g., with processing that has relatively low computational requirements.
For example, a listener, when listening to a suitably processed audio signal generated by the spatialization system and emitted by standard headphones, should be given the impression that there is a loudspeaker—called a “virtual” loudspeaker—located at an appropriate position relative to the listener's head. The listener should further be given the impression that he or she is listening in a desired listening environment. Thus, the spatialization process implemented by the spatialization system should provide a simulation of acoustic echoes in a desired listening environment that sounds natural. For example, the pattern of acoustic echoes created by the process should have different arrival times that are uncorrelated for each of the multiple virtual signals so as to provide for a realistic and natural sensation of room acoustics. Furthermore, it is desired that such a spatialization system provide for multiple virtual loudspeaker positions to be simulated at once with the system accepting a plurality of audio input signals each of which is to be “virtualized” at a different location.